The primary site of sontrol that determines the concentration of cyclic AMP in E. coli appears to be the rate of synthesis by adenylate cyclase. We are proceeding with a purification of the enzyme to determine its mechanism of regulation. The subunit structure, molecular weight, and properties of the purified enzyme will be characterized. Mutants with increased rates of cyclic AMP synthesis in vivo will be isolated and characterized. Reconstitution studies will be done to determine the mode of regulation and demonstrate such regulation in an in vitro system.